873 lines
27 KiB
PHP
873 lines
27 KiB
PHP
<?php
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namespace app\common\library;
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use Exception;
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/**
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* 安全过滤类
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*
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* @category Security
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* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
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* @copyright Copyright (c) 2014 - 2019, British Columbia Institute of Technology (https://bcit.ca/)
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* @license https://opensource.org/licenses/MIT MIT License
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* @link https://codeigniter.com
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* @author EllisLab Dev Team
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*/
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class Security
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{
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protected static $instance = null;
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/**
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* List of sanitize filename strings
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*
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* @var array
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*/
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public $filename_bad_chars = array(
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'../',
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'<!--',
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'-->',
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'<',
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'>',
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"'",
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'"',
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'&',
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'$',
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'#',
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'{',
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'}',
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'[',
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']',
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'=',
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';',
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'?',
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'%20',
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'%22',
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'%3c', // <
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'%253c', // <
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'%3e', // >
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'%0e', // >
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'%28', // (
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'%29', // )
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'%2528', // (
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'%26', // &
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'%24', // $
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'%3f', // ?
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'%3b', // ;
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'%3d' // =
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);
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/**
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* Character set
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*
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* Will be overridden by the constructor.
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*
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* @var string
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*/
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public $charset = 'UTF-8';
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/**
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* XSS Hash
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*
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* Random Hash for protecting URLs.
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*
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* @var string
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*/
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protected $_xss_hash;
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/**
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* List of never allowed strings
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*
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* @var array
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*/
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protected $_never_allowed_str = array(
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'document.cookie' => '[removed]',
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'(document).cookie' => '[removed]',
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'document.write' => '[removed]',
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'(document).write' => '[removed]',
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'.parentNode' => '[removed]',
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'.innerHTML' => '[removed]',
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'-moz-binding' => '[removed]',
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'<!--' => '<!--',
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'-->' => '-->',
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'<![CDATA[' => '<![CDATA[',
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'<comment>' => '<comment>',
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'<%' => '<%'
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);
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/**
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* List of never allowed regex replacements
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*
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* @var array
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*/
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protected $_never_allowed_regex = array(
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'javascript\s*:',
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'(\(?document\)?|\(?window\)?(\.document)?)\.(location|on\w*)',
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'expression\s*(\(|&\#40;)', // CSS and IE
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'vbscript\s*:', // IE, surprise!
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'wscript\s*:', // IE
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'jscript\s*:', // IE
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'vbs\s*:', // IE
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'Redirect\s+30\d',
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"([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
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);
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protected $options = [
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'placeholder' => '[removed]'
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];
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/**
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* Class constructor
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*
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* @return void
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*/
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public function __construct($options = [])
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{
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$this->options = array_merge($this->options, $options);
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foreach ($this->_never_allowed_str as $index => &$item) {
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$item = str_replace('[removed]', $this->options['placeholder'], $item);
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}
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}
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/**
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*
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* @param array $options 参数
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* @return Security
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*/
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public static function instance($options = [])
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{
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if (is_null(self::$instance)) {
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self::$instance = new static($options);
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}
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return self::$instance;
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}
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/**
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* XSS Clean
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*
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* Sanitizes data so that Cross Site Scripting Hacks can be
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* prevented. This method does a fair amount of work but
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* it is extremely thorough, designed to prevent even the
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* most obscure XSS attempts. Nothing is ever 100% foolproof,
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* of course, but I haven't been able to get anything passed
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* the filter.
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*
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* Note: Should only be used to deal with data upon submission.
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* It's not something that should be used for general
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* runtime processing.
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*
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* @link http://channel.bitflux.ch/wiki/XSS_Prevention
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* Based in part on some code and ideas from Bitflux.
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*
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* @link http://ha.ckers.org/xss.html
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* To help develop this script I used this great list of
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* vulnerabilities along with a few other hacks I've
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* harvested from examining vulnerabilities in other programs.
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*
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* @param string|string[] $str Input data
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* @param bool $is_image Whether the input is an image
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* @return string
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*/
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public function xss_clean($str, $is_image = false)
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{
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// Is the string an array?
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if (is_array($str)) {
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foreach ($str as $key => &$value) {
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$str[$key] = $this->xss_clean($value);
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}
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return $str;
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}
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// Remove Invisible Characters
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$str = $this->remove_invisible_characters($str);
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/*
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* URL Decode
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*
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* Just in case stuff like this is submitted:
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*
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* <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
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*
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* Note: Use rawurldecode() so it does not remove plus signs
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*/
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if (stripos($str, '%') !== false) {
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do {
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$oldstr = $str;
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$str = rawurldecode($str);
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$str = preg_replace_callback('#%(?:\s*[0-9a-f]){2,}#i', array($this, '_urldecodespaces'), $str);
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} while ($oldstr !== $str);
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unset($oldstr);
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}
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/*
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* Convert character entities to ASCII
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*
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* This permits our tests below to work reliably.
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* We only convert entities that are within tags since
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* these are the ones that will pose security problems.
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*/
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$str = preg_replace_callback("/[^a-z0-9>]+[a-z0-9]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
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$str = preg_replace_callback('/<\w+.*/si', array($this, '_decode_entity'), $str);
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// Remove Invisible Characters Again!
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$str = $this->remove_invisible_characters($str);
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/*
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* Convert all tabs to spaces
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*
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* This prevents strings like this: ja vascript
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* NOTE: we deal with spaces between characters later.
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* NOTE: preg_replace was found to be amazingly slow here on
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* large blocks of data, so we use str_replace.
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*/
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$str = str_replace("\t", ' ', $str);
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// Capture converted string for later comparison
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$converted_string = $str;
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// Remove Strings that are never allowed
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$str = $this->_do_never_allowed($str);
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/*
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* Makes PHP tags safe
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*
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* Note: XML tags are inadvertently replaced too:
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*
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* <?xml
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*
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* But it doesn't seem to pose a problem.
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*/
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if ($is_image === true) {
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// Images have a tendency to have the PHP short opening and
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// closing tags every so often so we skip those and only
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// do the long opening tags.
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$str = preg_replace('/<\?(php)/i', '<?\\1', $str);
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} else {
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$str = str_replace(array('<?', '?' . '>'), array('<?', '?>'), $str);
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}
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/*
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* Compact any exploded words
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*
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* This corrects words like: j a v a s c r i p t
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* These words are compacted back to their correct state.
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*/
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$words = array(
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'javascript',
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'expression',
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'vbscript',
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'jscript',
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'wscript',
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'vbs',
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'script',
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'base64',
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'applet',
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'alert',
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'document',
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'write',
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'cookie',
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'window',
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'confirm',
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'prompt',
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'eval'
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);
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foreach ($words as $word) {
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$word = implode('\s*', str_split($word)) . '\s*';
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// We only want to do this when it is followed by a non-word character
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// That way valid stuff like "dealer to" does not become "dealerto"
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$str = preg_replace_callback('#(' . substr($word, 0, -3) . ')(\W)#is', array($this, '_compact_exploded_words'), $str);
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}
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/*
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* Remove disallowed Javascript in links or img tags
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* We used to do some version comparisons and use of stripos(),
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* but it is dog slow compared to these simplified non-capturing
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* preg_match(), especially if the pattern exists in the string
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*
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* Note: It was reported that not only space characters, but all in
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* the following pattern can be parsed as separators between a tag name
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* and its attributes: [\d\s"\'`;,\/\=\(\x00\x0B\x09\x0C]
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* ... however, $this->remove_invisible_characters() above already strips the
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* hex-encoded ones, so we'll skip them below.
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*/
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do {
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$original = $str;
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if (preg_match('/<a/i', $str)) {
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$str = preg_replace_callback('#<a(?:rea)?[^a-z0-9>]+([^>]*?)(?:>|$)#si', array($this, '_js_link_removal'), $str);
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}
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if (preg_match('/<img/i', $str)) {
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$str = preg_replace_callback('#<img[^a-z0-9]+([^>]*?)(?:\s?/?>|$)#si', array($this, '_js_img_removal'), $str);
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}
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if (preg_match('/script|xss/i', $str)) {
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$str = preg_replace('#</*(?:script|xss).*?>#si', $this->options['placeholder'], $str);
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}
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} while ($original !== $str);
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unset($original);
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/*
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* Sanitize naughty HTML elements
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*
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* If a tag containing any of the words in the list
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* below is found, the tag gets converted to entities.
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*
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* So this: <blink>
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* Becomes: <blink>
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*/
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$pattern = '#'
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. '<((?<slash>/*\s*)((?<tagName>[a-z0-9]+)(?=[^a-z0-9]|$)|.+)' // tag start and name, followed by a non-tag character
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. '[^\s\042\047a-z0-9>/=]*' // a valid attribute character immediately after the tag would count as a separator
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// optional attributes
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. '(?<attributes>(?:[\s\042\047/=]*' // non-attribute characters, excluding > (tag close) for obvious reasons
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. '[^\s\042\047>/=]+' // attribute characters
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// optional attribute-value
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. '(?:\s*=' // attribute-value separator
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. '(?:[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*))' // single, double or non-quoted value
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. ')?' // end optional attribute-value group
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. ')*)' // end optional attributes group
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. '[^>]*)(?<closeTag>\>)?#isS';
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// Note: It would be nice to optimize this for speed, BUT
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// only matching the naughty elements here results in
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// false positives and in turn - vulnerabilities!
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do {
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$old_str = $str;
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$str = preg_replace_callback($pattern, array($this, '_sanitize_naughty_html'), $str);
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} while ($old_str !== $str);
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unset($old_str);
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/*
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* Sanitize naughty scripting elements
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*
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* Similar to above, only instead of looking for
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* tags it looks for PHP and JavaScript commands
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* that are disallowed. Rather than removing the
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* code, it simply converts the parenthesis to entities
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* rendering the code un-executable.
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*
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* For example: eval('some code')
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* Becomes: eval('some code')
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*/
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$str = preg_replace(
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'#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si',
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'\\1\\2(\\3)',
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$str
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);
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// Same thing, but for "tag functions" (e.g. eval`some code`)
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$str = preg_replace(
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'#(alert|prompt|confirm|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)`(.*?)`#si',
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'\\1\\2`\\3`',
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$str
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);
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// Final clean up
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// This adds a bit of extra precaution in case
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// something got through the above filters
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$str = $this->_do_never_allowed($str);
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/*
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* Images are Handled in a Special Way
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* - Essentially, we want to know that after all of the character
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* conversion is done whether any unwanted, likely XSS, code was found.
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* If not, we return TRUE, as the image is clean.
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* However, if the string post-conversion does not matched the
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* string post-removal of XSS, then it fails, as there was unwanted XSS
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* code found and removed/changed during processing.
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*/
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if ($is_image === true) {
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return ($str === $converted_string);
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* XSS Hash
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*
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* Generates the XSS hash if needed and returns it.
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*
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* @return string XSS hash
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*/
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public function xss_hash()
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{
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if ($this->_xss_hash === null) {
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$rand = $this->get_random_bytes(16);
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$this->_xss_hash = ($rand === false)
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? md5(uniqid(mt_rand(), true))
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: bin2hex($rand);
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}
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return $this->_xss_hash;
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}
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// --------------------------------------------------------------------
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/**
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* Get random bytes
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*
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* @param int $length Output length
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* @return string
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*/
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public function get_random_bytes($length)
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{
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if (empty($length) or !ctype_digit((string)$length)) {
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return false;
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}
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if (function_exists('random_bytes')) {
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try {
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// The cast is required to avoid TypeError
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return random_bytes((int)$length);
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} catch (Exception $e) {
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// If random_bytes() can't do the job, we can't either ...
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// There's no point in using fallbacks.
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return false;
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}
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}
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// Unfortunately, none of the following PRNGs is guaranteed to exist ...
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if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== false) {
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return $output;
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}
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if (is_readable('/dev/urandom') && ($fp = fopen('/dev/urandom', 'rb')) !== false) {
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// Try not to waste entropy ...
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stream_set_chunk_size($fp, $length);
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$output = fread($fp, $length);
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fclose($fp);
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if ($output !== false) {
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return $output;
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}
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}
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if (function_exists('openssl_random_pseudo_bytes')) {
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return openssl_random_pseudo_bytes($length);
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}
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return false;
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}
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// --------------------------------------------------------------------
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/**
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* HTML Entities Decode
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*
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* A replacement for html_entity_decode()
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*
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* The reason we are not using html_entity_decode() by itself is because
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* while it is not technically correct to leave out the semicolon
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* at the end of an entity most browsers will still interpret the entity
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* correctly. html_entity_decode() does not convert entities without
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* semicolons, so we are left with our own little solution here. Bummer.
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*
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* @link https://secure.php.net/html-entity-decode
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*
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* @param string $str Input
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* @param string $charset Character set
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* @return string
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*/
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public function entity_decode($str, $charset = null)
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{
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if (strpos($str, '&') === false) {
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return $str;
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}
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static $_entities;
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isset($charset) or $charset = $this->charset;
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isset($_entities) or $_entities = array_map('strtolower', get_html_translation_table(HTML_ENTITIES, ENT_COMPAT | ENT_HTML5, $charset));
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do {
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$str_compare = $str;
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// Decode standard entities, avoiding false positives
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if (preg_match_all('/&[a-z]{2,}(?![a-z;])/i', $str, $matches)) {
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$replace = array();
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$matches = array_unique(array_map('strtolower', $matches[0]));
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foreach ($matches as &$match) {
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if (($char = array_search($match . ';', $_entities, true)) !== false) {
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$replace[$match] = $char;
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}
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}
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$str = str_replace(array_keys($replace), array_values($replace), $str);
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}
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// Decode numeric & UTF16 two byte entities
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$str = html_entity_decode(
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preg_replace('/(&#(?:x0*[0-9a-f]{2,5}(?![0-9a-f;])|(?:0*\d{2,4}(?![0-9;]))))/iS', '$1;', $str),
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ENT_COMPAT | ENT_HTML5,
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$charset
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);
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} while ($str_compare !== $str);
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Sanitize Filename
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*
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* @param string $str Input file name
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* @param bool $relative_path Whether to preserve paths
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* @return string
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*/
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public function sanitize_filename($str, $relative_path = false)
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{
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$bad = $this->filename_bad_chars;
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if (!$relative_path) {
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$bad[] = './';
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$bad[] = '/';
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}
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$str = $this->remove_invisible_characters($str, false);
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do {
|
|
$old = $str;
|
|
$str = str_replace($bad, '', $str);
|
|
} while ($old !== $str);
|
|
|
|
return stripslashes($str);
|
|
}
|
|
|
|
// ----------------------------------------------------------------
|
|
|
|
/**
|
|
* Strip Image Tags
|
|
*
|
|
* @param string $str
|
|
* @return string
|
|
*/
|
|
public function strip_image_tags($str)
|
|
{
|
|
return preg_replace(
|
|
array(
|
|
'#<img[\s/]+.*?src\s*=\s*(["\'])([^\\1]+?)\\1.*?\>#i',
|
|
'#<img[\s/]+.*?src\s*=\s*?(([^\s"\'=<>`]+)).*?\>#i'
|
|
),
|
|
'\\2',
|
|
$str
|
|
);
|
|
}
|
|
|
|
// ----------------------------------------------------------------
|
|
|
|
/**
|
|
* URL-decode taking spaces into account
|
|
*
|
|
* @param array $matches
|
|
* @return string
|
|
*/
|
|
protected function _urldecodespaces($matches)
|
|
{
|
|
$input = $matches[0];
|
|
$nospaces = preg_replace('#\s+#', '', $input);
|
|
return ($nospaces === $input)
|
|
? $input
|
|
: rawurldecode($nospaces);
|
|
}
|
|
|
|
// ----------------------------------------------------------------
|
|
|
|
/**
|
|
* Compact Exploded Words
|
|
*
|
|
* Callback method for xss_clean() to remove whitespace from
|
|
* things like 'j a v a s c r i p t'.
|
|
*
|
|
* @param array $matches
|
|
* @return string
|
|
*/
|
|
protected function _compact_exploded_words($matches)
|
|
{
|
|
return preg_replace('/\s+/s', '', $matches[1]) . $matches[2];
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Sanitize Naughty HTML
|
|
*
|
|
* Callback method for xss_clean() to remove naughty HTML elements.
|
|
*
|
|
* @param array $matches
|
|
* @return string
|
|
*/
|
|
protected function _sanitize_naughty_html($matches)
|
|
{
|
|
static $naughty_tags = array(
|
|
'alert',
|
|
'area',
|
|
'prompt',
|
|
'confirm',
|
|
'applet',
|
|
'audio',
|
|
'basefont',
|
|
'base',
|
|
'behavior',
|
|
'bgsound',
|
|
'blink',
|
|
'body',
|
|
'embed',
|
|
'expression',
|
|
'form',
|
|
'frameset',
|
|
'frame',
|
|
'head',
|
|
'html',
|
|
'ilayer',
|
|
'iframe',
|
|
'input',
|
|
'button',
|
|
'select',
|
|
'isindex',
|
|
'layer',
|
|
'link',
|
|
'meta',
|
|
'keygen',
|
|
'object',
|
|
'plaintext',
|
|
'style',
|
|
'script',
|
|
'textarea',
|
|
'title',
|
|
'math',
|
|
'video',
|
|
'svg',
|
|
'xml',
|
|
'xss'
|
|
);
|
|
|
|
static $evil_attributes = array(
|
|
'on\w+',
|
|
'style',
|
|
'xmlns',
|
|
'formaction',
|
|
'form',
|
|
'xlink:href',
|
|
'FSCommand',
|
|
'seekSegmentTime'
|
|
);
|
|
|
|
// First, escape unclosed tags
|
|
if (empty($matches['closeTag'])) {
|
|
return '<' . $matches[1];
|
|
} // Is the element that we caught naughty? If so, escape it
|
|
elseif (in_array(strtolower($matches['tagName']), $naughty_tags, true)) {
|
|
return '<' . $matches[1] . '>';
|
|
} // For other tags, see if their attributes are "evil" and strip those
|
|
elseif (isset($matches['attributes'])) {
|
|
// We'll store the already filtered attributes here
|
|
$attributes = array();
|
|
|
|
// Attribute-catching pattern
|
|
$attributes_pattern = '#'
|
|
. '(?<name>[^\s\042\047>/=]+)' // attribute characters
|
|
// optional attribute-value
|
|
. '(?:\s*=(?<value>[^\s\042\047=><`]+|\s*\042[^\042]*\042|\s*\047[^\047]*\047|\s*(?U:[^\s\042\047=><`]*)))' // attribute-value separator
|
|
. '#i';
|
|
|
|
// Blacklist pattern for evil attribute names
|
|
$is_evil_pattern = '#^(' . implode('|', $evil_attributes) . ')$#i';
|
|
|
|
// Each iteration filters a single attribute
|
|
do {
|
|
// Strip any non-alpha characters that may precede an attribute.
|
|
// Browsers often parse these incorrectly and that has been a
|
|
// of numerous XSS issues we've had.
|
|
$matches['attributes'] = preg_replace('#^[^a-z]+#i', '', $matches['attributes']);
|
|
|
|
if (!preg_match($attributes_pattern, $matches['attributes'], $attribute, PREG_OFFSET_CAPTURE)) {
|
|
// No (valid) attribute found? Discard everything else inside the tag
|
|
break;
|
|
}
|
|
|
|
if (
|
|
// Is it indeed an "evil" attribute?
|
|
preg_match($is_evil_pattern, $attribute['name'][0])
|
|
// Or does it have an equals sign, but no value and not quoted? Strip that too!
|
|
or (trim($attribute['value'][0]) === '')
|
|
) {
|
|
$attributes[] = 'xss=removed';
|
|
} else {
|
|
$attributes[] = $attribute[0][0];
|
|
}
|
|
|
|
$matches['attributes'] = substr($matches['attributes'], $attribute[0][1] + strlen($attribute[0][0]));
|
|
} while ($matches['attributes'] !== '');
|
|
|
|
$attributes = empty($attributes)
|
|
? ''
|
|
: ' ' . implode(' ', $attributes);
|
|
return '<' . $matches['slash'] . $matches['tagName'] . $attributes . '>';
|
|
}
|
|
|
|
return $matches[0];
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* JS Link Removal
|
|
*
|
|
* Callback method for xss_clean() to sanitize links.
|
|
*
|
|
* This limits the PCRE backtracks, making it more performance friendly
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
|
|
* PHP 5.2+ on link-heavy strings.
|
|
*
|
|
* @param array $match
|
|
* @return string
|
|
*/
|
|
protected function _js_link_removal($match)
|
|
{
|
|
return str_replace(
|
|
$match[1],
|
|
preg_replace(
|
|
'#href=.*?(?:(?:alert|prompt|confirm)(?:\(|&\#40;|`|&\#96;)|javascript:|livescript:|mocha:|charset=|window\.|\(?document\)?\.|\.cookie|<script|<xss|d\s*a\s*t\s*a\s*:)#si',
|
|
'',
|
|
$this->_filter_attributes($match[1])
|
|
),
|
|
$match[0]
|
|
);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* JS Image Removal
|
|
*
|
|
* Callback method for xss_clean() to sanitize image tags.
|
|
*
|
|
* This limits the PCRE backtracks, making it more performance friendly
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
|
|
* PHP 5.2+ on image tag heavy strings.
|
|
*
|
|
* @param array $match
|
|
* @return string
|
|
*/
|
|
protected function _js_img_removal($match)
|
|
{
|
|
return str_replace(
|
|
$match[1],
|
|
preg_replace(
|
|
'#src=.*?(?:(?:alert|prompt|confirm|eval)(?:\(|&\#40;|`|&\#96;)|javascript:|livescript:|mocha:|charset=|window\.|\(?document\)?\.|\.cookie|<script|<xss|base64\s*,)#si',
|
|
'',
|
|
$this->_filter_attributes($match[1])
|
|
),
|
|
$match[0]
|
|
);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Attribute Conversion
|
|
*
|
|
* @param array $match
|
|
* @return string
|
|
*/
|
|
protected function _convert_attribute($match)
|
|
{
|
|
return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Filter Attributes
|
|
*
|
|
* Filters tag attributes for consistency and safety.
|
|
*
|
|
* @param string $str
|
|
* @return string
|
|
*/
|
|
protected function _filter_attributes($str)
|
|
{
|
|
$out = '';
|
|
if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches)) {
|
|
foreach ($matches[0] as $match) {
|
|
$out .= preg_replace('#/\*.*?\*/#s', '', $match);
|
|
}
|
|
}
|
|
|
|
return $out;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* HTML Entity Decode Callback
|
|
*
|
|
* @param array $match
|
|
* @return string
|
|
*/
|
|
protected function _decode_entity($match)
|
|
{
|
|
// Protect GET variables in URLs
|
|
// 901119URL5918AMP18930PROTECT8198
|
|
$match = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-/]+)|i', $this->xss_hash() . '\\1=\\2', $match[0]);
|
|
|
|
// Decode, then un-protect URL GET vars
|
|
return str_replace(
|
|
$this->xss_hash(),
|
|
'&',
|
|
$this->entity_decode($match, $this->charset)
|
|
);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Do Never Allowed
|
|
*
|
|
* @param string
|
|
* @return string
|
|
*/
|
|
protected function _do_never_allowed($str)
|
|
{
|
|
$str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);
|
|
|
|
foreach ($this->_never_allowed_regex as $regex) {
|
|
$str = preg_replace('#' . $regex . '#is', $this->options['placeholder'], $str);
|
|
}
|
|
|
|
return $str;
|
|
}
|
|
|
|
/**
|
|
* Remove Invisible Characters
|
|
*/
|
|
public function remove_invisible_characters($str, $url_encoded = true)
|
|
{
|
|
$non_displayables = array();
|
|
|
|
// every control character except newline (dec 10),
|
|
// carriage return (dec 13) and horizontal tab (dec 09)
|
|
if ($url_encoded) {
|
|
$non_displayables[] = '/%0[0-8bcef]/i'; // url encoded 00-08, 11, 12, 14, 15
|
|
$non_displayables[] = '/%1[0-9a-f]/i'; // url encoded 16-31
|
|
$non_displayables[] = '/%7f/i'; // url encoded 127
|
|
}
|
|
|
|
$non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S'; // 00-08, 11, 12, 14-31, 127
|
|
|
|
do {
|
|
$str = preg_replace($non_displayables, '', $str, -1, $count);
|
|
} while ($count);
|
|
|
|
return $str;
|
|
}
|
|
}
|